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OPTICAL FORCES NEAR MICRO-FABRICATED DEVICES
by
Camilo Andr´es Mej´ıa Prada
A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(PHYSICS)
December 2013
Copyright 2013 Camilo Andr´es Mej´ıa Prada

In this dissertation, I study optical forces near micro-fabricated devices for multi-particle manipulation. I consider particles of different sizes and compositions. In particular, I focus my study on both dielectric and gold particles as well as Giant Unilamellar Vesicles (GUVs). ❧ First, I consider optical forces near a PhC and establish the feasibility of a technique which we term Light-Assisted Templated Self-assembly (LATS). I exploit the guided resonance modes of a PhC to provide resonant enhancement of optical forces. The guided mode forms spatially distinct trapping patterns at different polarizations and wavelengths. I consider the possibility of assembling multi-particle patterns. Specially, I show how optical forces near a photonic crystal slab can be used to assist templated self-assembly and permit different particle pattern formation. Thus, a PhC will serve as an optically reconfigurable template for multi-particle trapping. ❧ Next, I calculate the optical force near a PhC micro-cavity for gold and dielectric particles ∼ 50 nm in diameter. Next, I use the electromagnetic field re-distribution around a trapped gold nano-particle to direct a metal-dielectric cluster formation. ❧ Finally, I explore optical forces near a Dual Beam Optical Trap (DBOT) and measure the bending modulus of a GUV ∼ 10 μm. First, I present a method to extract the bending modulus of the membrane from the area strain data. This method incorporates three-dimensional ray-tracing to calculate the applied stress in the DBOT within the ray optics approximation. I compare the optical force calculated using the ray optics approximation and Maxwell Stress Tensor method to ensure the approximation’s accuracy. Next, we apply this method to 3 populations of GUVs to extract the bending modulus of membranes comprised of saturated and monounsaturated lipids in both gel and liquid phases.

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OPTICAL FORCES NEAR MICRO-FABRICATED DEVICES
by
Camilo Andr´es Mej´ıa Prada
A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(PHYSICS)
December 2013
Copyright 2013 Camilo Andr´es Mej´ıa Prada